Drilling for gas, with gas
PARACHUTE—WPX Energy didn’t have to go far for a fuel source for the red-and-yellow Aztec Drilling rig operating last week in a side canyon up the Parachute Creek Valley.
A line running from a separator unit from four natural gas wells previously drilled on the same pad was providing a power source that saves the company thousands of dollars a day and reduces air pollution as well.
WPX teamed up with Aztec, based in Aztec, N.M., and the Canada-based Hyduke Energy Services oilfield services company to design the 136-foot-high, gas-powered rig that went into service in the Piceance Basin earlier this year. It first was tested by hooking it up to a natural gas line running down the street in the town where it was built in Canada, WPX spokeswoman Susan Alvillar said.
There’s no need for that in the Piceance Basin, where the rig takes advantage of the fruits of WPX’s own drilling.
“It’s natural gas that we produce through our wells and our pipelines,” Alvillar said.
The switch from a diesel-powered rig is producing a “monstrous” fuel savings because the gas being used costs 15 percent of the diesel cost, said Brad Moss, WPX’s district production manager. The Aztec rig is realizing $7,174 in fuel savings a day, which could result in $2.6 million in annual savings.
WPX also estimates it will result in a 24 percent reduction in total air emissions, with an 80 percent drop in compounds that contribute to ozone formation.
Not using diesel also eliminates the truck traffic and related air pollution required to deliver diesel to a rig.
WPX isn’t alone locally in turning to the very product it produces to power the rigs used in that production. Encana USA spokesman Doug Hock said his company began using natural-gas-powered rigs a couple of years ago.
Companywide, 57 percent of its fleet is now powered by natural gas. In the Piceance, the five rigs it’s now running include two that use gas produced in the field, and three that are powered by liquefied natural gas.
“It should be noted that these are ‘dual-fuel’ rigs that are also capable of utilizing diesel. All rigs use some amount of diesel (usually about 10 percent) to ignite the engine,” Hock said.
He said Encana is estimating about a 50 percent emissions reduction from the rigs, and a 30 percent average fuel savings.
The switch to gas-powered rigs by companies such as WPX and Encana comes as such companies also have been promoting the use of natural gas in vehicles.
“Our view is that it only makes sense we should utilize the product we’re producing” to power rigs, Hock said.
WPX said its fuel savings and emissions reductions with the Aztec rig have led to Nabors converting two of its rigs dedicated to WPX so they can run on both natural gas and diesel. WPX expects to have more of its Piceance rigs converted to dual-fuel use this year.
The gas it will use is metered to provide for payment of mineral owners.
The emissions reductions from gas-powered rigs come as the Colorado Department of Public Health and Environment prepares to consider new restrictions on air pollution related to oil and gas development. Alvillar said WPX participates in such rulemaking processes to try to ensure what’s passed by regulators is reasonable and safe. At the same time, said WPX district drilling manager Scott Brady, “We try to stay ahead of what we anticipate their rule changes might be.”
He said WPX’s early adoption of pitless drilling is an example of how the company has done just that over the years.
Besides being cleaner burning, the gas-fueled engines powering the Aztec rig are quieter than diesel-powered engines, another consideration when trying to reduce the impacts of drilling.
“You can’t stand right here and talk this close to any diesel rigs. We’d be screaming at each other,” Brady said while showing where the four 20-cylinder engines for the Aztec rigs are housed.
The engines generate electricity needed to run mud pumps and air compressors, operate hydraulic systems and meet other power needs.
Brady said gas-powered rigs have been available for 40 years, but the technology has advanced a long way. Also, a crucial part of WPX’s ability to operate such a rig is the fact that it already has drilled thousands of wells in the Piceance Basin and can count on a gas supply and the pipelines and other equipment needed to access it.
“Infrastructure is the key,” he said.